Hydrophobic Zeolite Research Articles

Thermodynamics of Polyethylene Glycol Intrusion in Microporous Water.

Polymers can be used to augment the properties of microporous materials, affording enhanced processability, stability, and compatibility. Manipulating polymers to target specific properties, however, requires detailed knowledge of how different polymers and microporous materials interact. Here, we report a study of the thermodynamics of polyethylene glycol (PEG) intrusion into a representative hydrophobic zeolite (silicalite-1) and metal-organic framework [ZIF-67; Co(2-methylimidazolate)2] in water, both of which can be formed into colloidally stable aqueous dispersions─termed "microporous water"─with dry, guest-accessible pore networks. Through a combination of O2 capacity measurements and isothermal titration calorimetry (ITC), we establish relationships between PEG intrusion behavior, polymer length, polymer end groups, and the structure of the microporous framework. In particular, we find that PEG intrusion is exothermic for silicalite-1 but endothermic for ZIF-67. Our results provide fundamental insights into polymer intrusion in microporous materials that should inform efforts to design composite solids and fluids with enhanced functionality.

Energy Efficient Methods for Product Separation and Concentration in Scalable CO2 Electrolysis

Facing the critical challenges of climate change and the escalating need for sustainable carbon management, the electrochemical reduction of CO2 emerges as a pivotal strategy for carbon recycling and the production of renewable energy. This approach addresses the imperative to mitigate CO2 emissions while harnessing the potential of electrochemical processes to transform CO2 into ethanol, a valuable renewable fuel. Unlike conventional methods reliant on biomass, which are limited by significant land use and potential environmental repercussions, electrochemical CO2 reduction offers a sustainable and efficient alternative. It enables the direct conversion of CO2 from its most oxidized state into more energetically favorable products through a process that integrates water splitting and CO2 hydrogenation into a single electrochemical step. This not only simplifies the conversion process but also facilitates the synthesis of products difficult to achieve through thermal processes, operating at or near ambient conditions to minimize energy consumption and environmental impact.Central to our study is the experimental approach using flow cells and MEA cells, which are primarily utilized for the large-scale electrochemical conversion of CO2. Both systems enable high-current density reactions (large-scale processing) by continuously flowing electrolyte, thus achieving mass processing capabilities. The dilution of reaction products within the electrolyte presents a significant challenge. Additionally, in the case of an MEA cell, there's the issue of the produced products undergoing oxidation at the anode, causing problems in stability during operation. Therefore, an economical method is needed to separate the products within the electrolyte.To overcome this, our research innovatively integrates a pervaporation system employing zeolite-based membranes within a flow cell configuration. This setup allows for the effective concentration of ethanol produced in the electrochemical reduction process, addressing the significant challenge of product dilution in the electrolyte.In our efforts to generate ethanol electrochemically, we utilized a Cu-based catalyst, conducting experiments in both neutral and alkaline electrolyte environments. It was observed that ethanol forms in real-time through the electrochemical reactions at concentrations lower than 1wt%. Furthermore, we successfully implemented a pervaporation process using a hydrophobic all-silica zeolite membrane. The pervaporation process using a hydrophobic all-silica zeolite membrane can selectively separate low concentrations of ethanol from catholyte due to the high selectivity of the zeolite membrane. In this study, we fabricated an MFI type silicalite-1 membrane on a tubular support and investigated the selective removal of ethanol in a water/ethanol mixture. The silicalite-1 membrane has a high Si/Al ratio and exhibits high molecular-level ethanol selectivity. In addition, the membrane has high chemical stability, making it applicable to long-term operation under harsh conditions.As a results, we achieved an ethanol concentration in the permeate of over 50% under conditions where < 1 wt% ethanol was present in the feed. This not only addresses the challenge of separating ethanol from highly diluted streams but also significantly improves the sustainability and scalability of the overall process.Our research underscores the potential of integrating advanced separation technologies in carbon recycling, offering a promising route for the environmentally friendly utilization of CO2 and contributing to the advancement of renewable energy solutionsRef) CO2 Electrolyzers. Chemical Reviews, 2024. Suppressing the liquid product crossover in electrochemical CO2 reduction. SmartMat, 2021, 2.1: 12-16. Energy-Efficient Ethanol Concentration Method for Scalable CO2 Electrolysis. ACS Energy Letters, 2023, 8.7: 3214-3220. Pure-water-fed, electrocatalytic CO2 reduction to ethylene beyond 1,000 h stability at 10 A. Nature Energy, 2024, 1-11. Identifying and alleviating the durability challenges in membrane-electrode-assembly devices for high-rate CO electrolysis. Nature Catalysis, 2023, 6.11: 1042-1051.

The effect of perfluoroalkyl chain length and the type of acid group on PFAS adsorption from water

Widespread use of per- and polyfluoroalkyl substances (PFAS) poses significant ecological and health risks due to their non-degradability in the environment and consequent bioaccumulation in humans. In this work, we carried out a systematic computational study to unravel the effect of perfluorinated carbon chain length and the type of acid head group on the adsorption mechanism of PFAS from water. We considered the adsorption of perfluoroalkyl carboxylic acids (PFCA) and perfluoroalkyl sulfonic acids (PFSA) with chain lengths of three to eight perfluorinated carbons in hydrophobic all-silica zeolite Beta. Molecular dynamics (MD) simulations coupled with enhanced sampling calculations showed that adsorption free energies of both PFCA and PFSA decreased with increasing number of perfluorinated carbons. Calculated free energies further showed that PFCA and PFSA, which are anions in water, must overcome substantially large interfacial energy barriers to be adsorbed in hydrophobic pores. Subsequent ab initio MD simulations revealed that PFCA and PFSA gain a proton at the water–zeolite interface and are eventually adsorbed in neutral form. Breakdown of guest–host interaction energies into hydrophobic and polar components showed that hydrophobic interactions dominate PFCA adsorption whereas polar interactions are dominant in PFSA adsorption. This is due to sulfonic acid giving rise to stronger electrostatic interactions and the rearrangement of the electron density distribution in the perfluorinated carbon chain, which render the hydrophobic interactions relatively weaker. Our study reveals that a combination of adsorbents that provide optimized hydrophobic and polar interactions should be used for the capture of diverse PFAS from water.

Computational Screening of Hydrophobic Zeolites for the Removal of Emerging Organic Contaminants from Water.

The pollution of water resources by pharmaceuticals and agents of personal care products (PPCPs) poses an increasingly pressing issue that has received considerable attention from scientists and government agencies alike. Hydrophobic zeolites can serve as selective adsorbents to remove these contaminants from aqueous solution. So far, the adsorption of PPCPs in zeolites has often been investigated in case studies focusing on a small number of contaminants and one or a few zeolites. We present a computational screening approach to investigate the interaction of 53 PPCPs with 14 all-silica zeolites, aiming at a more comprehensive understanding of factors that are beneficial for a strong host-guest interaction and thus an efficient adsorption. The systems are modelled on the classical force field level of theory, allowing for the efficient computational treatment of a large number of PPCP-zeolite combinations and evaluated in terms of the interaction energy between PPCP and zeolite framework. For selected PPCP-zeolite combinations additional Free Energy Perturbation simulations are employed to compute Free Energies of Transfer between the aqueous phase and the adsorbed state. These results can serve as a starting point for experimental studies of relevant PPCP-zeolite combination or more in-depth theoretical investigations.

Ethylene Adsorption on Alkali-Hydrophobic Zeolite Y

Zeolites HY with different hydrophobicity having Si/Al ratios of 10, 100 and 750 were modified by an ion exchange process with nitrate solutions of alkali cations in the concentration range 0.1 - 100 mM. The modified samples were characterized by ICP-OES, XRD and surface analysis with N2-adsorption. The ethylene adsorptivities of these modified zeolites were measured under degassed and non-degassed conditions. All zeolites showed the enhancement in ethylene adsorptivity upon modification, while the K+ ions modified ones showed the best enhancement. The modified hydrophobic zeolites with Si/Al ratios of 100 and 750 showed no differences in adsorptivity under the degassed and non-degassed conditions. However, for less hydrophobic zeolite (Si/Al = 10), the adsorption under the degassed condition was much higher than the adsorption under the non-degassed condition. These results indicate that the modified hydrophobic zeolites with Si/Al ratios of 100 and 750 are suitable as ethylene scavengers at ambient conditions. HIGHLIGHTS Zeolites Y with different Si/Al ratios were modified by alkali nitrate solutions The ethylene adsorptivities were measured under degassed and non-degassed conditions Zeolites showed better ethylene adsorptivity upon modification with alkali cation K+ ions modified zeolite showed the best enhancement Modified zeolites (100 and 750) suited as ethylene adsorbent at ambient conditions GRAPHICAL ABSTRACT

Hydrophobic nanosheet silicalite-1 zeolite for iodine and methyl iodide capture

Effective capture of radioactive iodine from nuclear fuel reprocessing is of great importance for public safety as well as the secure utility of nuclear energy. In this work, a hydrophobic nanosheet silicalite-1 (NSL-1) zeolite with an adjustable size was developed for efficient iodine (I2) and methyl iodide (CH3I) adsorption. The optimized all-silica zeolite NSL-1 exhibits an excellent I2 uptake capacity of 553 mg/g within 45 min and a CH3I uptake capacity of 262 mg/g within 1 h. Benefiting from the reduced thickness and enhanced porosity, microporous NSL-1 possesses enhanced iodine adsorption capacity and fast adsorption kinetics, which is a considerable high value among inorganic materials. Unexpectedly, the remarkable characters of high hydrophobicity, acid-resistance and anti-oxidation endow it a higher iodine uptake capacity than traditional aluminosilicate zeolites. More importantly, the high uptake selectivity toward I2 possessed by NSL-1 owing to its hydrophobic skeleton under simulated dynamic conditions. The low cost, facile and scalable synthesis of NSL-1 further highlights great prospects for applications in the nuclear industry. This work provides useful insights for designing efficient adsorbents for iodine capture.

Calorimetric Heats of Intrusion of LiCl Aqueous Solutions in Hydrophobic MFI-Type Zeosil: Influence of the Concentration.

For the first time, we report calorimetric measurements of intrusion of aqueous LiCl solutions in a hydrophobic pure siliceous MFI zeolite (silicalite-1) under high pressure. Our results show that the intrusion heats are strongly dependent on the LiCl concentration. The intrusion process is endothermic for diluted solutions (molar H2O/LiCl = 12) as well as for water, but it becomes exothermic for a concentration close to saturation (molar H2O/LiCl = 4). Analysis of the data in the framework of wetting thermodynamics shows that besides surface wetting, other phenomena occur during intrusion, such as hydrogen-bond weakening and composition change. In all cases, water is preferentially intruded so that the intruded phase becomes more diluted than the bulk solution. In the case of the most diluted solution, only water molecules seemed to be intruded. Furthermore, silicalite-1 is shown to be very stable in the presence of LiCl solution, with no noticeable structural and textural modifications observed after intrusion.

Quality and quantitative traits of non-alcoholic beer with flavour-improved taste

The non-alcoholic and low-alcohol beer market has grown significantly in recent years and is predicted to continue growing. However, non-alcoholic and low-alcohol beers have organoleptic problems and are not recognized by many consumers. The increasing popularity of alcohol-free beers (AFBs) fosters the industry's interest in delivering the best possible product. Yet, a remaining sensory issue of AFBs is the over-perception of wort flavor, caused by elevated concentrations of small volatile flavor compounds (i.e.aldehydes)still remains. Previously, molecular sieves (hydrophobic ZSM-5 type zeolites) were found as most suitable to remove these flavors by adsorption with high selectivity from the AFBs. In this work, a flavor-improved beer is produced at a pilot-scale using this novel technology, and its chemical composition, sensory profile, and stability are evaluated against a reference. Aldehyde concentrations in the flavor-improved product were found 79–93% lower than in the reference. The distinct difference was confirmed with a trained sensory panel and could be conserved even after three months of ageing at 30ºC. Future work will focus on the process design to scale up this technology. It is established that the release of a new kind of beer is economically profitable, since the expansion of the range contributes to a more complete use of production capacity, and consequently, reduced costs per unit of production, which ultimately leads to an increase in the profit of the enterprise.

Hydrophobic modification of zeolite-supported platinum catalysts for complete oxidation of toluene

Zeolite-supported noble metal nanoparticles have been reported as active catalysts for complete oxidation of volatile organic compounds (VOCs) due to the combination of advantages of zeolite supports and noble metal species, where introducing more Al species (reduction of SiO2/Al2O3 ratios, SAR) and increasing hydrophobicity for zeolite supports are favorable for the complete oxidation of VOCs. Unfortunately, introduction of more Al species in the zeolite frameworks normally reduces the hydrophobicity of zeolite crystals. To overcome this problem, we rationally synthesize hydrophobic zeolites with low SAR by anchoring methyl group, exhibiting exceptionally catalytic performances in the complete oxidation of toluene at very low temperature (T90 at 144 °C) after loading Pt species (1 wt%). Characterizations of the catalysts show a vital role of hydrophobic zeolites for adsorption of more toluene and fast desorption of water. The strategy for preparation of hydrophobic zeolite-supported noble metal catalysts might offer an alternative way to develop highly efficient heterogeneous catalysts for the complete oxidation of VOCs in the future.

Development of Silicalite-1 encapsulated Cu-ZnO catalysts for methanol synthesis by CO2 hydrogenation

Converting CO2 into fuels and valuable chemicals such as methanol has been gaining significant attention as a favorable solution for reducing greenhouse gas emissions. Although Cu-ZnO-based catalysts are promising candidates for this reaction since methanol is selectively produced at the Cu-ZnO interface, Cu are not stable at elevated temperatures (500–600 K), leading to decrease in the surface areas of Cu and Cu-ZnO interface due to thermal aggregation of Cu. Furthermore, the generation of H2O as a by-product in the CO2 hydrogenation does not only accelerate the aggregation of Cu, but also inhibits an intermediate (formate species) formation for methanol. This paper reports the development of a novel catalyst, annotated as CuPS@S-1 by immobilizing Cu phyllosilicate (CuPS) as the Cu source within hydrophobic zeolite of Silicalite-1 particles (S-1). Cu@S-1 was obtained after the reduction CuPS@S-1 and the size of the Cu particles was approximately 2.4 nm. Cu@S-1 exhibited a higher CO2 hydrogenation activity and methanol selectivity than Cu/S-1 prepared by an impregnation method. To further improve the methanol production activity, ZnO was loaded onto Cu@S-1 to form a Cu-ZnO interface. ZnO/Cu@S-1 was obtained by the impregnation of CuPS@S-1 powder with an ethanol solution containing zinc acetate, followed by calcination and reduction. The obtained catalyst exhibited a better methanol production yield where the space–time yield for methanol based on the Cu weight exceeded 1200 mgmethanol gCu−1h−1.

Metal nanocatalysts confined within hydrophobic zeolite for selective hydrogenation of nitroaromatics

Metal nanocatalysts confined within hydrophobic zeolite for selective hydrogenation of nitroaromatics

Toward the development of sensors for lung cancer: The adsorption of 1-propanol on hydrophobic zeolites.

A healthy breath is mainly composed of water, carbon dioxide, molecular nitrogen, and oxygen and it contains many species, in small quantities, which are related to the ambient atmosphere and the metabolism. The breath of a person affected by lung cancer presents a concentration of 1-propanol higher than usual. In this context, the development of specific sensors to detect 1-propanol from breath is of high interest. The amount of propanol usually detected on the breath is of few ppb; this small quantity is a handicap for a reliable diagnostic. This limitation can be overcome if the sensor is equipped with a pre-concentrator. Our studies aim to provide an efficient material playing this role. This will contribute to the development of reliable and easy to use lung cancer detectors. For this, we investigate the properties of a few hydrophobic porous materials (chabazite, silicalite-1, and dealuminated faujasite). Hydrophobic structures are used to avoid saturation of materials by the water present in the exhaled breath. Our experimental and simulation results suggest that silicalite -1 (MFI) is the most suitable structure to be used as a pre-concentrator.

Modification of Fe on hydrophobic ZSM-5 zeolite: Optimization of adsorption and catalytic performance for decomposition of VOCs at low-temperature

The conjugation of high adsorption and excellent catalytic characteristics is desirable for the removal of volatile-organic-compounds (VOCs) at low-temperatures. In this study, ZSM-5 zeolites with varying Si/Al ratios (15, 30, 100, and 200) were synthesized using the hydrothermal-method to assess their adsorption capability for VOCs. Among them, the ZSM-5(30) sample exhibited a well-defined zeolite structure, exceptional hydrophobicity, a high surface area (SBET), and micropores, resulting in a higher toluene adsorption capacity of 135 mg/g compared to other adsorbents. Additionally, the ZSM-5(30) sample demonstrated excellent regenerative stability in both dry and humid environments. Consequently, ZSM-5(30), identified as the most effective adsorbent, was subjected to loading with various amounts of Fe metal for the catalytic-oxidation of toluene at low-temperatures. Due to its abundant oxygen-vacancies, adequate acid-sites, and various active oxygen-species, the Fe0.2/ZSM-5(30) catalyst (Fe/(Si + Al) = 0.2) not only exhibited a high adsorption capacity for toluene with good stability over five successive cycles but also demonstrated excellent performance in the catalytic oxidation of toluene. The complete conversion of toluene was attained at temperatures approximately 200 °C, with a gas hourly space velocity (GHSV) of 20,000 mL/(g∙h), and maintained stability for 40 h. Furthermore, in-situ diffuse-reflectance infrared-Fourier-transform-spectroscopy (DRIFTS) and gas chromatography-mass spectrometry (GC–MS) results, along with the Mars-Van-Krevelen model, were utilized to elucidate the adsorption and oxidation mechanism of toluene. The unique adsorption and oxidation capabilities of Fe0.2/ZSM-5(30) for toluene indicate its promising potential for the removal of VOCs in real industrial-environments. This study provides valuable insights for the design of high-performance bifunctional materials for the adsorption and catalytic-oxidation of VOCs.

A study of the thermal regeneration of loaded hydrophobic and hydrophilic zeolites after adsorption in the liquid phase

The paper aims to show a search method for optimal conditions of 3A, 13X, ZSM-5 zeolite thermal regeneration after adsorption from a liquid water-isopropanol mixture. Comparative TGA-DTG results for heating of wet zeolites with different structure and hydrophobicity showed characteristic effects corresponding to the optimal temperature of zeolite regeneration. The consequences of overheating and collapse of the 3A, 13X, ZSM-5 zeolite structure at temperatures of 850, 900, 1000 °C, respectively, were recorded with XRD method. Moreover, XRD and NIR/DRS tests of loaded and regenerated zeolite samples showed interaction of adsorbate and co-adsorbed water with adsorbent and revealed influence of adsorption and regeneration processes on the adsorbent structure. Investigations of the regeneration of the zeolite 3A bed after adsorption of water from the isopropanol solution in the temperature swing adsorption (TSA) process were carried out by heating the bed with inert gas at 250 °C and different purge gas streams in the range of 1.68–2.40 kg/h. Four stages of wet bed regeneration were distinguished, which corresponded to the effect observed during TGA-DTG tests. For each stage, the specific demand for purge gas and energy was determined depending on the gas stream and its minimum value of 2.16 kg/h was indicated.

Highly hydrophobic zeolite ZSM-8 with perfect framework structure obtained in a strongly acidic medium

The synthesis of zeolites in a strongly acidic medium is a new and nearly unexplored chemistry field. In addition to the previously reported silicalite-1 and the several clathrasils, this paper elaborates that one more material of unique properties could be successfully crystallized in the strongly acidic fluoride medium. A pure-silica zeolite ZSM-8 has been obtained using tetraethylammonium ion as a structure-directing agent. Rietveld refinement proves that ZSM-8 is of the MFI topology, i.e., it is another silicalite-1 but different in framework distortions. Moreover, the discrete and uniform crystals of the acidic-medium synthesized pure-silica ZSM-8 possess a substantially perfect framework structure and thus hydrophobic surfaces. This remarkable character renders the material an ideal adsorbent for discriminating molecules on the polarity basis, which is desired in developing green separation processes. C3H8, CH4, and CO2 are chosen as examples respecting their different polarities and tested for the adsorptive parameters.

A two-step organic modification strategy for improving surface hydrophobicity of zeolites

The organic modification using a silane coupling agent can significantly improve the surface hydrophobicity of zeolite powders. However, insufficient hydroxyl group content on surface of the zeolites greatly limits the immobilization dosage of the agent, making the samples less hydrophobic. In this study, a two-step organic modification strategy using 1,2-bis(triethoxysilyl)ethane (BTESE) and dodecyltrimethoxysilane (DTMS) was adopted and developed to synthesize highly hydrophobic organic modified zeolite powders. The results showed that the BTESE modification could significantly increase the hydroxyl group content on the surface of zeolite powders, and relatively higher amount of DTMS could be then modified on the BTESE-modified samples. The mean critical surface tension, water vapor adsorption capacity, and water drop contact angle/penetration time of the 0.5% DTMS modified 10% BTESE-zeolite powders were 46.20 mN /m, 27 mg/g, and 142°/˃25 s, while those of the 0.5% DTMS modified zeolite powders were > 71.60 mN/m, 45 mg/g, and 124°/19.48 s, respectively, indicating that the sample synthesized by this two-step method was much more hydrophobic than the sample synthesized by traditional method. This two-step organic modification method appears to be a simple and effective way to prepare highly hydrophobic zeolite powders.

Lewis acidity and substituent effects influence aldehyde enolization and C–C coupling in beta zeolites

The Claisen-Schmidt condensation between propanal and benzaldehyde was used a model aldol reaction to assess the reactivity of tetravalent framework Lewis acid sites (Ti, Zr, Sn, Hf) in hydrophobic beta zeolites (M-*BEA) and determine rates of enolization and carbon–carbon (C–C) bond formation along with selectivities among cross- and self-condensation products. Rates of enolate formation during liquid phase reactions (393 K) span nearly 100-fold, depending on the identity of the metal heteroatom, and correlate with enthalpies for adsorption of pyridine in liquid-filled pores of M-*BEA, as measured by isothermal titration calorimetry. Comparisons among adsorption enthalpies suggest that tetrahedrally substituted Zr and Hf are more effective Lewis acids than Sn and Ti for coordinating aldehydes within these environments. Ratios of initial rates of C–C coupling between propanal and benzaldehyde compared to propanal self-condensation were less than unity for all M-*BEA catalysts. These selectivity patterns reflect the combination of electronic and steric effects imposed by the larger aromatic substituent at the carbonyl carbon atom and its concerted interactions with the Lewis acid site, which causes rates for nucleophilic attack of enolates to benzaldehyde to be far less than those to propanal.

Decorating {0 0 1} TiO2 nanosheets on hydrophobic NaY zeolite: An efficient deactivation-resistant photocatalyst for gaseous toluene removal

Photocatalysis is regarded as a promising in situ air purification technology for the removal of volatile organic compounds. However, the deactivation of photocatalysts remains a serious issue that needs to be addressed. Herein, we report a novel dual-functional photocatalyst (TiO2@HYZ) with spatially separated catalytic sites and adsorption sites, which has been obtained by combining hydrophilic {001} TiO2 nanosheets with hydrophobic NaY zeolite. TiO2@HYZ showed excellent photocatalytic activity for the degradation of gaseous toluene under UV irradiation in humid air. The optimized TiO2@HYZ-2 (containing 45.7 wt% TiO2) achieved 96.6% toluene removal and 87.4% mineralization within 120 min. The specific reaction rate constant of TiO2@HYZ-2, pristine TiO2 and P25 normalized by the unit amount of TiO2 during the photocatalytic degradation process were calculated to be 0.481, 0.230 and 0.250 min−1 g−1, respectively. Moreover, TiO2@HYZ-2 showed superior durability, maintaining stable performance over repeated toluene degradation processes, even at high toluene concentration, whereas pristine TiO2 incurred severe deactivation with increasing number of photocatalysis cycles. The significantly enhanced activity and anti-deactivation property was attributed to a synergistic effect between HYZ and TiO2 in the catalyst structure, which strengthened the adsorption of toluene on HYZ and facilitated effective separation of photoexcited charge carriers on TiO2, thus avoiding the deposition of degradation intermediates on the active sites and simultaneously improving mineralization. This work provided a new perspective for the design of efficient and deactivation-resistant photocatalysts for air pollution remediation.

A surface-induced coating strategy for constructing hydrophobic zeolite composite to enhance the toluene adsorption in humid environment

Capturing volatile organic compounds (VOCs) under humid conditions using zeolites suffers from the dramatically decreasing adsorption capability with relative humidity (RH) increase. Herein, a surface-induced polymer coating method is proposed to design hydrophobic zeolite. The as-synthesized novel hydrophobic Y zeolite@hypercrosslinked polymer composite (Y@P) is demonstrated with excellent adsorption capability for VOCs. In particular, the toluene adsorption capacity of Y@P-2-80 composite is two times higher than that of Y zeolite, and the Qwet/Qdry values are 97.2% at 90 %RH, indicating that the toluene adsorption capability of Y@P-2-80 is almost unaffected by vapor. The proposed surface-induced polymer coating method provides a promising and universal strategy for effective VOCs capture under wet conditions using zeolites with enhanced hydrophobicity.

Experimental Study on the Effects of Applied Electric Field on Liquid Infiltration into Hydrophobic Zeolite

A nanofluidic energy absorption system (NEAS) is composed of nanoporous material and functional liquid with high energy absorption density. Applying an electric field to adjust the energy absorption characteristics of a nanofluidic system will open broader prospects for its application. In the current work, ZSM-5 zeolite was adopted as the nanoporous material and water, a 25% KCl solution, and a saturated KCl solution were adopted as functional liquids to configure NEASs. Pressure-induced infiltration experiments were carried out to study the infiltration and defiltration characteristics of the NEASs under the action of an applied electric field. The results show that the introduction of an applied electric field can weaken the hydrogen bonds between molecules, thus reducing the equivalent surface tension and contact angle, changing the infiltrability of liquid molecules into the nanopores, and reducing the infiltration pressure of the system. In an electrolyte solution/zeolite system, the anions and cations move close to the two plate electrodes under the action of an external electric field, and the fluid properties in the central zone of the pressure chamber are close to the water/zeolite system. For both an ultra-low conductivity liquid and an electrolyte solution/zeolite system, applying an electric field can effectively improve the relative outflow rate of liquid, thus improving the reusability of the system.